Lightweight Clutch/Flywheel - BMW Forum

thejobman · 05-04-2006, 01:24 PM

A friend of mine is telling me to do a "lightweight clutch/flywheel" upgrade... Allegedly, it makes the car feel like it has another 40 hp (even though the hp does not actually go up, rather parasitic hp loss goes down instead)...

Has anyone on this forum done this to their e39 540? What track times do you run? Does it hurt the car's everyday use functionality?

Thanks,

///M Power · 05-04-2006, 01:42 PM

It's a lightweight flywheel and clutch.

It's not a gain of horsepower. It's a reduction in rotational mass at the flywheel which allows for quicker revving through the powerband. the downside is that many lightweight flywheels produce a nasty sound all the time which almost makes the car sound as if it's engine is in bad shape. Another disadvantage is a lightweight flywheel is slightly mroe difficult to drive, especially if you're on the freeway in stop and go traffic.

thejobman · 05-04-2006, 02:26 PM

I have heard some manufacturers claim that their LtWt flywheel kit has little or no rattle... is this a myth?

In addition, I keep seeing "CVD" in ppl's sigs... what is that?

Sorry for being such a newb... thanks,

thejobman · 05-04-2006, 02:29 PM

err, sorry, I meant "CDV", not "CVD"

thejobman · 05-04-2006, 02:45 PM

NVM, Found this:

http://www.zeckhausen.com/CDV.htm

In a thread burried in the tech forum, thanks anyway

Eric S. · 05-04-2006, 07:36 PM

Quote:

Originally Posted by thejobman

NVM, Found this:

http://www.zeckhausen.com/CDV.htm

In a thread burried in the tech forum, thanks anyway

I did the CDV delete job as well, and it's a definite "must do". Judging by the mods your car already has, there's a good chance your car already has had a CDV-ectomy. Check thru your papers or with the previous owner.

Either way it is a very easy job to do. I bought Dave Z's gutted out CDV, but with your car out of warranty, there's really no need to buy the dummy CDV. The only other reason to swap out the real CDV for a gutted one is to make it easier to do - apparently a lot of clutch fluid can leak out if you remove the old CDV and try to just hook the clutch line up directly to the slave cylinder.

Well, guess what? A lot of fluid leaked out during my swap anyway, and I ended up going through the fun of bleeding the air out of my clutch system.

So I recommend you just save the $35 and simply delete the CDV, not replace it with anything, get yourself bathed in clutch fluid, and then work the air out of the system and you'll be fine.

I've heard mixed reviews regarding lightweight aftermarket clutches. be careful and do a search for posts on the topic. I remember one guy having a problem with his UUC clutch and getting basically nothing but smart-aleck remarks from UUC about it. When my clutch's time is up, I believe I will go with OEM, in case you were wondering.

BTW, the flywheel on your 540 pretty much needs replacing when you replace the clutch anyway. Apparently the "dual mass" flywheel is not machineable, and the cheapest OEM flywheel I've found is nearly $700 from Crevier BMW. Here is a great write-up on 540 clutch replacement:
http://members.cox.net/anmillar1/index.htm

tracetrimble · 05-04-2006, 08:50 PM

In general, factory parts are designed for longevity and driveability. Lightening anything in the drivetrain generally makes the car feel more jerky, like a race car, which is kinda missing the point with a bimmer.

saltshaker185 · 05-05-2006, 10:41 PM

getting a lightweight flywheel/clutch IMO is one of the best mods i have done... it just seems soo much faster in aceleration because it does go faster! i dont relaly know times but i think you should get it...

thejobman · 05-05-2006, 11:24 PM

Saltshaker- Everyone else is saying that this modification will make my car run like crap. Is this a conservative view point?

You and my friend (who is the head ///M mechanic at a local dealer) feel it is a "must get"...

As of now, I guess I will consider installing the ltwt flywheel upgrade when it is time to replace my clutch... Plus I use to drive a Mustang GT with 4:10's in the rear diff... I can’t really imagine it being nearly as worse as that… And even that was “bearable”

I guess I will just continue to look into it, I have time before the clutch goes…

saltshaker185 · 05-05-2006, 11:42 PM

personally, if you find a good quality flywheel and all then it really isnt that bad... the only problem i have with it is bumper to bumper traffic, its not as easy to control your clutch... its kind of an all go or all off situation...

thejobman · 05-06-2006, 10:31 PM

hmmm... I do find myself in bumper to bumper traffic often...

I guess I will have to think it over a bit more,

Thanks for the input!

saltshaker185 · 05-06-2006, 10:50 PM

yeah... i get it ocasionally, but it really depends on how well you are on a clutch... i tend to feel like i have alot of control over my car and all so its not toooo bad for me... you just gotta go easy on it...

lwebb12 · 05-09-2006, 09:06 PM

Quote:

Originally Posted by tracetrimble

In general, factory parts are designed for longevity and driveability. Lightening anything in the drivetrain generally makes the car feel more jerky, like a race car, which is kinda missing the point with a bimmer.

I have a lightweight flywheel and stage 3 clutch...still smooth.